Mr. Marwan’s story — a tale overflowing with the suspense and ruthless duplicity of a spy novel — began to take shape in the spring of 1969. He had come to London, ostensibly to consult a Harley Street doctor about a stomach ailment. He chose to be examined by a doctor whose offices had been used previously for a covert meeting between King Hussein of Jordan and the general director of the Israeli prime minister’s office."